Currently, the calibration of thermometers is usually performed in calibration baths, ovens or fixed point systems. A corresponding fixed point cell is described in DE 102004027072 B3, for example. In this case, the measurement deviation of the thermometer to be calibrated is determined at determined temperature values, also referred to as fixed temperature values. The thermometer is uninstalled from the measuring point, plugged into the calibration system and calibrated for this purpose. However, this type of calibration is complicated due to the required removal of the thermometer. Consequently, it has been known from the state of the art to calibrate a thermometer in the installed state. Such a fixed point cell, miniaturized and integrated in a thermometer, has become known from Offenlegungsschrift DE 19941731 A1. In such case, it is suggested to plug the temperature sensor to be calibrated into a cell located in a measuring component; the cell is filled with a fixed point substance, most often a metal or a eutectic alloy. When the fixed point substance is brought to melting or solidification temperature, the thermometer measures this melting point temperature. The measured melting point temperature can then be compared to a stored melting point temperature. In such case, the requirement of an additional cell for encapsulating the fixed point substance is a disadvantage. In this way, dynamics of the thermometer, i.e. the response time to temperature changes, worsen. Moreover, the fixed point substance can exit from the cell in some circumstances and so destroy the thermometer.
A method for ascertaining the Curie temperature of ferromagnetic materials has become known from patent DE 4032092 C2, in which the abrupt change of the heat absorption in the region of the Curie temperature is not detectable by measuring using a differential scanning thermal analyzer, and, consequently, additional apparatuses for applying a magnetic field are provided.
Offenlegungsschrift DE 19805184 A1 describes a method for ascertaining the temperature of a piezoelectric element. In such case, the temperature of the piezoelement is determined via the capacitance of the piezoelement.
Additionally, DE 102005029464 B4 relates to the compensation of piezo influences on an integrated semiconductor circuit.
DE 102004003853 B4 relates to integrated circuit arrangements in a semiconductor substrate and to a concept for compensating the negative influence of a mechanical stress component in the semiconductor substrate on the parameter accuracy and parameter stability of a circuit arrangement integrated on the semiconductor substrate.
Finally, DE 69130843 T2 relates to a method and apparatus for determining the temperature of a piezoelectric crystal oscillator.
Offenlegungsschrift DE 19954164 A1 describes a sensor for measuring mechanical loading acting on a surface of a mechanical component.
Another way of calibrating a plurality of integrated temperature sensors in situ has become known from patent EP 1247268 B2. For this, one or a number of reference elements, in the form of temperature sensors, are installed in a thermometer component in addition to a primary temperature sensor. These usually differ from the primary temperature sensor in construction or material used and consequently have, in comparison to the primary temperature sensor, different aging effects and characteristic curve drifts. Thus, for example, semiconductors known as NTC/PTC resistors are used as reference elements in parallel with the primary Pt100 resistance sensors. The significant disadvantage of these arrangements is that only sensors with different characteristic curves or aging characteristics can be used as a reference. These must still be more exactly known or the characteristic curve changes due to aging should be smaller than those of the primary temperature sensor to be monitored. Particularly in the case of the calibration/validation of resistance thermometers, which are already very stable long term in broad temperature ranges, this has not been attainable so far.